The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
In a non-volatile memory, which may be referred to as a cross-point non-volatile memory and may include, for example, a phase change memory (PCM), memory cells of the PCM may typically be set to a first threshold voltage or a second threshold voltage, dependent upon the data being stored in the memory cell. The first threshold voltage may correspond to a first state of the memory cell, and the second threshold voltage may correspond to a second state of the memory cell. In order to identify which of the two states the memory cell is in, a read voltage may be applied to the memory cell, and compared to the threshold voltage of the memory cell. Based on that comparison, the state of the memory cell may be identified. However, in some embodiments the threshold voltages may shift over time, a phenomenon referred to as “drift.”